Effects of carbon dioxide deficiency and metal toxicity on biological oxygen demand

Abstract

In this study, the effects of carbon dioxide (CO 2 ) deficiency on the biological growth under respirometric conditions, first-and second-order biological oxygen demand (BOD) progressions using two different BOD measurement techniques and metal toxicity effects on the respirometric BOD are investigated. The effects of CO 2 deficiency in the growth of bacteria and related effects on the first-and second-stage BOD progressions are investigated using various media with respirometers in comparison with the BOD dilution method. CO 2 deficiency causes significant retardations on the growth of bacteria and the second-stage respirometric BOD values are suppressed. CO 2 seems to be an essential nutrient for the growth of microorganisms and for the oxygen uptake progressing rates. HgCl 2 , HgSO 4 , CuSO 4 , K 2 Cr 2 O 7 , ZnSO4 and Al 2 (SO 4 ) 3 inorganic metal compounds cause significant retardations in the respirometric BOD values obtained from a synthetic autotrophic medium. Effects are found to be dependent on the applied concentrations of these chemicals in the medium.